It is known in a portable data carrier, for example in a chip card, to either deny or to permit, in dependence on the state of a mechanical switch, a contactless communication between the portable data carrier and for example a corresponding reading device. For this purpose, the mechanical switch interrupts a galvanic connection or establishes such a connection. However, such mechanical switches are comparatively difficult to produce and are furthermore subject to wear.
As an alternative approach it is known to select an operation mode of a chip card in dependence on a detected state. Thus for example a contactless communication is denied by an internal control mechanism, if the chip card is supplied with an external voltage via the contact surfaces of the chip module.